The invention relates to a device for preventing the formation of fog or icing on a transparent body, for instance, the windshield of a motor vehicle.
A customary method for preventing icing of the windshield of a parked motor vehicle consists of placing a heat-insulating protective foil or a cardboard on the outside and to clamp it by means of the raised windshield wipers. With this method, contamination of the protective foil by the dust and moisture sticking to the windshield cannot be avoided, and it is necessary to renew the material within a short time. If the temperature varies, the protective foil can freeze on, and the windshield will cool down considerably. Upon subsequent heating of the interior, the formation of condensed water on the inside results which can impair the view on the road and cause the traffic safety problems. After use, the dirty foil must furthermore be placed in the motor vehicle which is often troublesome or difficult.
Another method is to heat the windshield directly or indirectly by an electric resistance wire. This, however, requires a large amount of electric energy which necessitates, among other things, oversized batteries. The field of view is also impaired by the firmly anchored resistance wires and is considered as extremely disturbing in most situations.
It is an object of the invention to develop a device of this kind which can be handled easily and cleanly while avoiding the above-mentioned disadvantages, and which is characterized by good efficiency while consuming no, or only an insignificant amount, of electric energy.